What is WSDL?
Web Services Description Language (WSDL) is a format for describing a Web Services interface. It is an XML file that describes the technical details of how to implement a web service, more specifically the URI, port, method names, arguments and data types.
Since WSDL is XML, it is both human-readable and machine-consumable, which aids in the ability to call and bind to services dynamically. It is a way to describe services and how they should be bound to specific network addresses.
WSDL has three parts defined as below:
- Definitions – Generally expressed in XML and include both data type definitions and message definitions that use the data type definitions. These definitions are usually based upon some agreed upon XML vocabulary.
- Operations – Describes actions for the messages supported by a Web service. There are three types of operations:
- One way – Messages sent to Web service does not require response.
- Request/Response – Proper response is sent to Client after request is been served by Web service.
- Notification – Messages sent to multiple receivers subscribed to Web services.
- Service bindings – Describes connection of port types to a port. A port is defined by associating a network address with a port type. A collection of ports defines a service. This binding is commonly created using SOAP but other forms may be used like CORBA Internet Inter-ORB Protocol (IIOP), DCOM, .NET, Java Message Service (JMS), or WebSphere MQ to name a few.